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Abstract

The efficacy of the insecticide lannate as a molluscicide for the control of two land snail
species widely distributed all over the Nile Delta, E. vermiculata and M. contiana was
investigated. The rates of mortalities of both snail species are depend on the dose and time
of exposure to the insecticide, lannate. The higher mortality rates were noticed at doses
higher than LD50. However, at all doses, the mortality rates increased by the time and
most mortalities occurred over five days post insecticide administration, the maximum
mortality rates of 95 and 75 were observed for E. vermiculata and M. contiana after 108
hours by doses of 34.8 and 39.4 mgkg, respectively. Both species of the land snails
treated with lannate have shown pathological alterations in the digestive gland and in the
gonads. The vacuolated and swollen digestive cells and presence of numerous yellowish
brown granules residual bodies in the cells are the most pathological changes observed.
These indicate that lannate have toxic effects in cellular damage of the digestive glands of
the snails which could be correlated with the disturbed enzyme activities. The male and
female gametes on the other hand, are severely affected and probably the male gametes
are inhibited to develop to the late stages of spermatogenesis. This indicates that the
insecticide used did not cause a complete cessation of gametogenesis

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